All terrain vehicles are relatively light weight with a relatively low center of gravity. Early three wheel versions had knobby tires having small square block elements and a relatively shallow tread depth.
Later versions of "Quad runners" or 4 wheel type ATV's were developed and have been more widely accepted due to their improved stability. Horsepower increases and improvements in both vehicle suspension and chassis has resulted in vehicles capable of relatively high speed and much greater load carrying capacity.
The tires used on these vehicles are operated at very low pressures in the 0.7 bar (10 psi) or less range. The tires are very wide with relatively large air chambers which assist in absorbing shock and vibration. The tires generally have nominal rim diameters of 36 cm (14 inches) or less and overall diameters of 66 cm (26 inches) or less.
Often the rear tires are of a slightly larger size than the more lightly loaded front tires.
In aggressive off-road applications the tires must have a very open tread pattern that employs elongated lugs which provide effective straightline or drawbar traction to enable the vehicle to climb hilly and rough terrain, as shown in U.S. Design Pat. No. 308,038. Additionally, the tread must provide excellent lateral traction for vehicle stability during turning maneuvers as is disclosed in U.S. Pat. No. 5,259,429.
The tire disclosed in that patent employs a repeating pattern of long, intermediate length and short lugs arranged to provide improved traction. The arrangement of these lugs is such that each lug wraps completely over the tread shoulder portion. The lugs are also circumferentially relatively closely spaced such that numerous lugs are in the footprint of the tire at any one time. The tire made according to this prior art invention is considered one of the best mud tires in its class according to its manufacturer.